• 한국광학회지
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• 제31권5호
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• pp.205-212
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• 2020

풍력 터빈 시스템의 성능에서 블레이드는 매우 중요한 역할을 하지만 복잡하고 불규칙적인 하중에 의한 손상에 취약하며 유지 보수 비용도 많이 든다. 따라서 블레이드 제조를 완료한 후에 결함을 찾아내고 일정 기간 사용한 후에 블레이드 손상을 찾아내는 것이 매우 중요하다. 본 연구에서는 풍력 터빈 블레이드의 주재료인 유리섬유와 탄소섬유 패널에서 내부 결함을 검출할 수 있는 새로운 방법을 제안하고자 한다. 블레이드 제조 또는 작동 중에 발생할 수 있는 복합재료의 섬유 파단을 모사하기 위해 적층된 재료의 중간층에 직경 5 mm의 홀을 가공한 후에, 비접촉 측정 기술인 이미지 상관법(digital image correlation, DIC)을 사용하여 내부 결함을 검출하였다. 인장시험기를 사용하여 가공된 시편에 인장 하중을 가하면서 이미지 상관법 시스템으로 변화되는 시편의 이미지를 저장하고 분석하였다. 유리섬유 복합재료 시편에서는 인장 하중 방향으로 5%의 변형률부터 내부 결함이 검출되었으며 탄소섬유의 경우에는 1%의 변형률부터 내부 결함이 검출되었다. 재료 특성에 따라 내부 결함 주변에 일정 수준의 변형률 차이가 발생함에 따라 결함이 검출됨을 이미지 상관법 시스템으로 증명하였다.

• 동의생리병리학회지
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• 제19권1호
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• pp.218-223
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• 2005

According to the Chinese and Korean medicinal and herbal literature, SSG(Silsosangami) is effective for the treatment of inflammation, hyperlipemia and arteriosclerosis. The pharmacological action of SSG has been limitedly studied in regard to ischemic infarction. This herbal medicine has been shown to express diverse activities such as immunomodulating, anti-infarction, anti-allergic and anti-inflammatory effects. Antisclerotic effects of SSG in experimentally induced atherosclerosis in rabbits have also been reported. However, pharmacological mechanisms of SSG on lipid metabolism and atherosclerosis formation are poorly understood. The present paper reports the effect of extracts obtained from SSG on endotoxin-induced experimental DIC in rats. Also, these were tested for their effect on endotoxin-induced blood platelet aggregation, thrombin-induced conversion of fibrinogen and fibrinolysis in vitro experiments with aspirin as a positive agent. The anti-thrombic properties of SSG were also investigated by means of analytical parameters of bood composition. The extracts of SSG and its seven herbs, except Cnidii Rhizoma and Carthami Flos, inhibited the endotoxin-induced DIC and thrombosis in rats. Also the extract inhibited the endotoxin-induced decrease in blood platelets and fibrinogen, and endotoxin-induced increase in fibrin degradation products (FDP) on disseminated intravascular coagulation in normal rats.

• 대한한방부인과학회지
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• 제19권1호
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• pp.139-154
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• 2006

Objective : This experimental study was carried out to investigate anti-coagulation effects and mechanism of Hongdeung-tang on the dissentimenated intravascular coagulation Methods : Each 10 rats were classified as normal gorup, control group and treated group. The control group was given a 0.5mg/ml endotoxin intra-vein injection and was occurred Disseminated Intravascular Coagulation(DIC). The treated group were orally administrated 1ml Hongdeung-tang concentration once a day for 6 days and then it was treated the same as the control group. We took the blood from heart and were investigated number of Platelet and white blood cell(WBC), fibrinogen concentration, prothrombin time(PT), activated partial thromboplastin time(APTT), interleukin-6(IL-6), Tumor Necrosis $Factor-{\alpha}(TNF-{\alpha})$, Prostaglandin $E2(PGE_2)$ from them. Results : There were a statistically significant increase of platelet and fibrinogen concentration in the treated group compared to the treated group. The PT was a significantly reduced in treated group compared to the control group. There was no significant change in numbers of WBC and APTT between control and treated group. On the contrary, the number of PT, IL-6, $TNF-{\alpha}$, $PGE_2$ were significantly decreased in treated group compared to the control group. Conclusion : DIC which was occurred by endotoxin intravenous injection seems to related to the increase of IL-6, $TNF-{\alpha}$, $PGE_2$ and Hongdeung-tang has an effect that supress those factors. we can assume Hongdeung-tang has an anti-coagulation effect by those supressing effect.

• Design & Manufacturing
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• 제15권2호
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• pp.23-29
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• 2021

The specific strength of magnesium alloy is four times that of iron and 1.5 times that of aluminum. For this reason, its use is increasing in the transportation industry which is promoting weight reduction. At room temperature, magnesium alloy has low formability due to Hexagonal closed packed (HCP) structure with relatively little slip plane. However, as the molding temperature increases, the formability of the magnesium alloy is greatly improved due to the activation of other additional slip systems, and the flow stress and elongation vary greatly depending on the temperature. In addition, magnesium alloys exhibit asymmetrical behavior, which is different from tensile and compression behavior. In this study, a jig was developed that can measure the plane deformation behavior on the surface of a material in tensile and compression tests of magnesium alloys in warm temperature. A jig was designed to prevent buckling occurring in the compression test by applying a certain pressure to apply it to the tensile and compression tests. And the tensile and compressive behavior of magnesium at each temperature was investigated with the developed jig and DIC equipment. In each experiment, the strain rate condition was set to a quasi-static strain rate of 0.01/s. The transformation temperature is room temperature, 100℃. 150℃, 200℃, 250℃. As a result of the experiment, the flow stress tended to decrease as the temperature increased. The maximum stress decreased by 60% at 250 degrees compared to room temperature. Particularly, work softening occurred above 150 degrees, which is the recrystallization temperature of the magnesium alloy. The elongation also tended to increase as the deformation temperature increased and increased by 60% at 250 degrees compared to room temperature. In the compression experiment, it was confirmed that the maximum stress decreased as the temperature increased.

• Journal of the Optical Society of Korea
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• 제18권5호
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• pp.523-530
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• 2014

Machine material and structural strain are critical factors for appraising mechanical properties and safety. Particularly in three and four-point bending tests, which appraise the deflection and flexural strain of an object due to external force, measurements are made by the crosshead movement or deflection meter of a universal testing machine. The Digital Image Correlation (DIC) method is one of the non-contact measurement methods. It uses the image analyzing method that compares the reference image with the deformed image for measuring the displacement and strain of the objects caused by external force. Accordingly, the advantage of this method is that the object's surface roughness, shape, and temperature have little influence. However, its disadvantage is that it requires extensive time to compare the reference image with the deformed image for measuring the displacement and strain. In this study, an algorithm is developed for DIC that can improve the speed of image analysis for measuring the deflection and strain of an object caused by a three-point bending load. To implement this algorithm for improving the speed of image analysis, LabVIEW 2010 was used. Furthermore, to evaluate the accuracy of the developed fast correlation algorithm, the deflection of an aluminum specimen under a three-point bending load was measured by using the universal test machine and DIC measurement system.

• International Journal of Concrete Structures and Materials
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• 제10권2호
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• pp.189-203
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• 2016

This paper investigates on the use of advanced optical measurement methods, i.e. 3D coordinate measurement machines (3D CMM) and stereo-vision digital image correlation (3D DIC), for the mechanical analysis of shear deficient prestressed concrete members. Firstly, the experimental program is elaborated. Secondly, the working principle, experimental setup and corresponding accuracy and precision of the considered optical measurement techniques are reported. A novel way to apply synthesised strain sensor patterns for DIC is introduced. Thirdly, the experimental results are reported and an analysis is made of the structural behaviour based on the gathered experimental data. Both techniques yielded useful and complete data in comparison to traditional mechanical measurement techniques and allowed for the assessment of the mechanical behaviour of the reported test specimens. The identified structural behaviour presented in this paper can be used to optimize design procedure for shear-critical structural concrete members.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1998년도 가을 학술발표논문집 Vol.25 No.2 (2)
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• pp.102-104
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• 1998

본 시스템은 현재 연구 개발중인 정보에이전트 시스템의 일부로서 특정분야에 대한 사용자의 관심 주제에 관련된 정보와 함께 적절한 문서를 제공하는 지식 기반 시스템이다. 이러한 목적을 위해서 본 시스템의 지식베이스는 구조적인 방식으로 표현된 BKB(Biology Knowledge Base)와 DIC(DICtionary)로 구성된다. DIC는 특정분야에서 일반적으로 사람들이 사용하는 용어와 학명을 기준으로 하는 시스템에서 사용하는 용어와의 관계와 그러한 용어들간의 동의어 관계를 갖고 있다. 또한 BKB는 동물에 관련된 지식베이스로써 상위.하위 개념과 함께 사용자가 원하는 정보를 제공하기 위해 객체의 속성과 이에 관계된 값들을 포함한다. 본 시스템은 문서를 검색할 때 사용자 초기 질의를 상위.하위 개념 그리고 동의어로 확장할 뿐만 아니라 사용자 의도의 정확한 표현을 위해서 제공하는 다양한 질의 형식에 따른 질의 처리 결과로도 확장하므로 효과적인 문서 검색 결과를 보인다.

• 한국가시화정보학회지
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• 제19권3호
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• pp.77-83
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• 2021

Solid oxide fuel cell (SOFC) operates at high temperatures in range of 600-800℃. Since layers of SOFC are composed of different substances, different thermal expansion in SOFC can result in defects under high temperature conditions. For understanding relation between temperature field and the thermal deformation in SOFC, temperature and strain field were simultaneously estimated using thermographic phosphors by optical measurement. Temperature fields were obtained by the life-time method, and the temperature differences of one specimen was checked with thermocouple. The thermal deformation was estimated by digital image correlation (DIC) method with extracted phosphorescence images. To investigate the deformation accuracy of DIC measurement, thermographic phosphors were coated with and without grid pattern on aluminum surface. Simultaneous measurement of temperature fields and thermal deformation were carried out for YSZ. This study will be helpful to multi-sensing of temperature field and thermal deformation on SOFC cells.

• Clinical and Experimental Pediatrics
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• 제48권8호
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• pp.820-825
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• 2005

목 적 : 감염과 질병상태의 유용한 인자인 열의 존재와 정도를 좀더 손쉽고 정확하게 확인하기 위해, 고막체온계 및 이마체온계의 정확성과 유용성을 평가하고자 하였다. 방 법 : 2004년 1월 1일부터 12월 31일 까지 중앙대학교 부속 병원에 입원하여 치료받았던 환아 중 무작위로 1,050명을 선출하여 대상으로 하였으며, 수은 체온계, 고막 체온계(BRAUN IRT $3020^{(R)}$) 및 이마 체온계(HubDIC $DOTORY^{(R)}$)로 동시에 체온을 측정하였고 이를 비교, 분석하여 상관관계를 조사하였다. 결 과 : 고막 체온계와 이마 체온계의 측정치는 각각 표준 검사인 수은 체온계의 측정치와 유의한 상관관계 및 상호 교환성을 가졌으며, 양측 고막 간, 그리고 고막 체온계와 이마 체온계 사이에서도 유의한 상관관계를 보였다. 발열에 대한 고막 체온계의 민감도는 오른쪽과 왼쪽에서 각각 81.1%, 82.4%였고, 양성 예측률은 각각 81.8%, 73.6%였다. 이마 체온계의 민감도는 83.3%였으며, 양성 예측률은 74.4%였다. 결 론 : 고막 체온계(BRAUN IRT $3020^{(R)}$) 및 이마형 체온계(HubDIC $DOTORY^{(R)}$)가 액와형 수은체온계와 통계적으로 유의한 상관성 및 일치성을 보이며(P<0.05), 또한 발열에 대한 민감도 및 양성 예측률이 매우 높아 일상의 가정에서나 병원에서 진료목적으로, 연구 목적으로 체온 측정하는 데 유용하게 사용될 수 있을 것으로 본다.

• Computers and Concrete
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• 제24권6호
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• pp.527-539
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• 2019

In this paper, the fracture characteristics of concrete specimens with different notch depths under three-point flexural loads are studied by finite element and fracture mechanics methods. Firstly, the concrete beams (the size is 700×100×150 mm) with different notch depths (a=30 mm, 45 mm, 60 mm and 75 mm respectively) are tested to study the influence of notch depths on the mechanical properties of concrete. Subsequently, the concrete beams with notch depth of 60 mm are loaded at different loading rates to study the influence of loading rates on the fracture characteristics, and digital image correlation (DIC) is used to monitor the strain nephogram at different loading rates. The test results show that the flexural characteristics of the beams are influenced by notch depths, and the bearing capacity and ductility of the concrete decrease with the increase of notch depths. Moreover, the peak load of concrete beam gradually increases with the increase of loading rate. Then, the fracture energy of the beams is accurately calculated by tail-modeling method and the bilinear softening constitutive model of fracture behavior is determined by using the modified fracture energy. Finally, the bilinear softening constitutive function is embedded into the finite element (FE) model for numerical simulation. Through the comparison of the test results and finite element analysis, the bilinear softening model determined by the tail-modeling method can be used to predict the fracture behavior of concrete beams under different notch depths and loading rates.